Storage bags are well known. Such bags can be manufactured from a variety of materials including, but not limited to, paper and plastic. Paper is often the material of choice when the article or articles to be stored are dry or solid goods. Paper is also often selected for aesthetic or traditional reasons as with upscale clothing stores providing loop handled paper bags, or grocery stores where kraft paper bags have traditionally been employed.
However, if perishable goods such as, but not limited to, food products, are to be stored, paper has a very limited effectiveness given its porosity and inability to be sealed. Plastic bags, particularly those manufactured from thermoplastic materials such as, but not limited to, high and low density polyethylene, have accordingly become the dominant product of choice in the area of food storage bags. Such material is fluid impermeable, relatively inexpensive, and can be manufactured in transparent form thereby facilitating content identification.
Such thermoplastic bags are also typically provided so as to be recloseable and substantially sealable. One common approach to provide such features employs closure members at a top edge of a bag having first and second thermoplastic layers folded or heat sealed along bottom and first and second side edges. The closure members may be provided in the form of mating male and female profiles such as those provided by the present assignee under the ZIPLOC® trademark. The male and female profiles are also typically manufactured from plastic, with the male profile including a linear tab adapted to be interlocked with a linear groove of the female profile.
The male and female profiles can be connected to close the bag by pinching and pulling across the closure members along the length of the top edges. Such motion can be accomplished as with the thumb and forefinger of a user, or through the use of a sliding element mounted to the male and female profiles, as is the case with bags provided by the present assignee under the ZIPLOC® trademark as well.
While such bags have been met with extraordinary commercial success from their inception until the present day, the assignee continues to improve its product offerings. One area, which the assignee has identified as being advantageously improved, involves the ability of the bag to pop open, as well as maintain an open configuration. More specifically, as indicated above, such bags typically include closed bottom and side edges and an open, but recloseable, top edge. If the bag is not gusseted, the top edges tend to stay adjacent one another regardless of whether the male and female profiles are engaged. This may be problematic, as when attempting to fill the bag, in that the user must hold the bag open with one hand while filling the bag with the other. Moreover, the user is often frustrated in not knowing if the bag is in fact open.
The industry has therefore begun to provide such thermoplastic storage bags with a stay-open feature. Such bags may be provided with semi-rigid plastic strips provided proximate the top edges of the bag. The strips may be molded about an arcuate mandrel or cylinder so as to have a relaxed, bowed configuration and a stressed, flattened configuration. When the male and female closure elements are engaged, the strips are held in the stressed, flattened configuration, but when the closure members are disengaged, the strips return to their relaxed, bowed configuration, thereby holding the bag open. U.S. Pat. No. 4,898,477 is one example of such a stay-open bag.
While such bags provide a stay-open feature, it would be advantageous to provide alternative forms of thermoplastic storage bags, having a stay open feature, which are less expensive to manufacture and which provide improved ability to snap into an open configuration immediately upon disengaging the male and female profiles.